bridge: Prepare for forwarding another bridge group addresses

If a bridge is an 802.1ad bridge, it must forward another bridge group
addresses (the Nearest Customer Bridge group addresses).
(For details, see IEEE 802.1Q-2011 8.6.3.)

As user might not want group_fwd_mask to be modified by enabling 802.1ad,
introduce a new mask, group_fwd_mask_required, which indicates addresses
the bridge wants to forward. This will be set by enabling 802.1ad.

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 10 insertions, 2 deletions

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 1b797c42ef5f..568cccd39a3d 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -378,6 +378,7 @@ void br_dev_setup(struct net_device *dev)
 
         br->stp_enabled = BR_NO_STP;
         br->group_fwd_mask = BR_GROUPFWD_DEFAULT;
+        br->group_fwd_mask_required = BR_GROUPFWD_DEFAULT;
 
         br->designated_root = br->bridge_id;
         br->bridge_max_age = br->max_age = 20 * HZ;
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 04d6348fd530..366c43649079 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -177,6 +177,8 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
         p = br_port_get_rcu(skb->dev);
 
         if (unlikely(is_link_local_ether_addr(dest))) {
+                u16 fwd_mask = p->br->group_fwd_mask_required;
+
                 /*
                  * See IEEE 802.1D Table 7-10 Reserved addresses
                  *
@@ -194,7 +196,8 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
                 case 0x00:      /* Bridge Group Address */
                         /* If STP is turned off,
                            then must forward to keep loop detection */
-                        if (p->br->stp_enabled == BR_NO_STP)
+                        if (p->br->stp_enabled == BR_NO_STP ||
+                            fwd_mask & (1u << dest[5]))
                                 goto forward;
                         break;
 
@@ -203,7 +206,8 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 
                 default:
                         /* Allow selective forwarding for most other protocols */
-                        if (p->br->group_fwd_mask & (1u << dest[5]))
+                        fwd_mask |= p->br->group_fwd_mask;
+                        if (fwd_mask & (1u << dest[5]))
                                 goto forward;
                 }
 
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 13e570e8b0fc..4eba348a985b 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -35,6 +35,8 @@
 #define BR_GROUPFWD_DEFAULT     0
 /* Don't allow forwarding control protocols like STP and LLDP */
 #define BR_GROUPFWD_RESTRICTED  0x4007u
+/* The Nearest Customer Bridge Group Address, 01-80-C2-00-00-[00,0B,0C,0D,0F] */
+#define BR_GROUPFWD_8021AD      0xB801u
 
 /* Path to usermode spanning tree program */
 #define BR_STP_PROG     "/sbin/bridge-stp"
@@ -226,6 +228,7 @@ struct net_bridge
         bool                            nf_call_arptables;
 #endif
         u16                             group_fwd_mask;
+        u16                             group_fwd_mask_required;
 
         /* STP */
         bridge_id                       designated_root;